We're a little late, but Real Life got in the way, so here we finally are. Canonical, the commercial sponsor of Ubuntu, announced today that Ubuntu 9.10 Desktop Edition has been released. This version focusses on improvements in cloud computing on the server using Eucalyptus, further improvements in boot speed, as well as development on Netbook Remix. The related KDE, Xfce, and other variants have been released as well. Update by ELQ: Just a quick note to say that one of my Creative Commons videos was selected to be part of Ubuntu's Free Culture Showcase package that comes by default with the new Ubuntu version!

I'm sorry, but either your memory is faulty, or you actually bought an expensive add-on sound card that could do full blown hardware mixing

This is what I could do: open two Sound Recorder and have them play at the same time. A P90 NT4 laptop we keep for testing can have Winamp playing + Simcity 2000 with audio. I have told it that what it is doing is impossible, but it stubbornly continues to work.
Perhaps the capability is in the driver, and not using the OS?

Back to the present: My workstation has an AC97. Apps are compiled with ALSA support. Two sound apps cannot use the sound card at the same time. My recourse is: reinstall Linux. Go distro-hopping until the problems are resolved and pray there are no new ones.